Could what’s in this little container keep our planet healthy? The simple reality is we need to find a way to put carbon back into the soil, and making something called ‘biochar’ is perhaps the best way to do that. While attending the World Renewable Energy Forum in Denver, it was hard not to be attracted to what could be the lowest tech solution to our carbon problem — simply stabilize it and put it back into the ground from where it came. Biochar is a valuable soil amenity and fuel source, so its potential is just being tapped. The net-carbon negative process is being taken very seriously as the best, and thus far, only proven way to store carbon for the long term in large quantities.
‘Biochar’ was coined in 2007 and means charcoal applied to soil — its potential usefulness was made famous by a study of 500 year old soil in the Amazon. Terra Preta de Indio, or dark earth, was created by indigenous cultures near the Amazon river by placing charcoal back into the marginal clay which in turn pushed pH levels to 5.5 from 3.5, making it some of the best soil in Brazil and improving land productivity by 3 times.
Pryolysis is the key chemical reaction to make biomass, or simply stated plants, into a long term carbon fixed medium. Adding heat to biomass without introducing oxygen changes the sugars into fixed carbon. Tom Miles of TR Miles Technical Consultants explained how when carbon rich material is added to soil, it will stay there for hundreds, if not thousands of years. Biochar infused soil is used to reclaim landscapes, used on turf, farms or nurseries, and even on green roofs. The biochar’s surface is home for active microbes and retains water. When added as a soil amenity in optimal percentages, there will be an improvement of plant growth.
Jonah Levine of Biochar Solutions walked us through how they take wood chips and ‘cook’ them at 350-700 degrees, and then separate the gas, dust and charcoal using a towable rig. The hotter the pryolysis the more gas is produced and cooler temperatures result in more biochar. The gas is burned at the rig and can be used to dry the feedstock and heat the raw material that makes the process a net-carbon negative process.
But proponents of biochar who see it as a way to geoengineer our way out of a global warming nightmare need to think big. In Japan perhaps 1/3 of rice husks are turned into biochar, Black is Green, or BIG, in Australia is a huge mobile biochar machine, and even larger ICM Gasifiers are used in Kansas. The new kid on the block, Cool Planet Energy Systems, is looking to make large semi-mobile units that can produce gas, synthetic diesel, and other fuels. They promise that if the resulting biochar is put into the soil, their fuels will have twice the total carbon reduction of even solar and wind. Clearly if biochar is to become the great alternative to our one way carbon lifestyle, many industries will need to cooperate to stake its potential in the ground.